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1.
Surveys were conducted in five voyages in Haizhou Bay and its adjacent coastal area from March to December 2011 during full moon spring tides. The ichthyoplankton assemblages and the environmental factors that affect their spatial and seasonal patterns were determined. Totally 35 and 12 fish egg and larvae taxa were identified, respectively. Over the past several decades, the egg and larval species composition has significantly changed in Haizhou Bay and its adjacent waters, most likely corresponding with the alteration of fishery resources, which are strongly affected by anthropogenic activities and climate change. The Bray-Curtis dissimilarity index identified four assemblages: near-shore bay assemblage, middle bay assemblage and two closely related assemblages(near-shore/middle bay assemblage and middle/edge of bay assemblage). The primary species of each assemblage principally reflected the spawning strategies of adult fish. The near-shore bay assemblage generally occurred in near-shore bay, with depths measuring 20 m, and the middle bay assemblage generally occurred in the middle of bay, with depths measuring 20 to 40 m. Spatial and seasonal variations in ichthyoplankton in each assemblage were determined by interactions between biological behavioral traits and oceanographic features, particularly the variation of local conditions within the constraint of a general reproductive strategy. The results of Spearman's rank correlation analysis indicated that both fish egg and larval abundance were positively correlated with depth, which is critical to the oceanographic features in Haizhou Bay.  相似文献   

2.
The spatio-temporal patterns of macrofaunal fouling assemblages were quantitatively investigated in the nearshore waters of the South China Sea. The work was undertaken by deploying seasonal panels at two sites (H-site, L-site) for one year, and the fouling communities on the panels were examined and analyzed. The results indicated that species composition of assemblages was obviously different between the two sites. At both sites the assemblages were characteristic with solitary dominant species throughout the year, with Amphibalanus reticulates dominating at H-site and Hydroides elegans at L-site. Shannon index and biomass of the assemblages varied with depth and season at both sites. At H-site the total biomass in summer and autumn were significantly higher than those in spring and winter, while at L-site the assemblage biomass also differed significantly among the four seasons, and the greatest biomass occurred at the depth of 2.0 m in winter. The abundance of all seasonal samples in non-metric multidimensional scaling was clustered as one group at L-site and three groups at H-site. The environmental factors were more likely to be related to the variation of fouling assemblages. Furthermore, it also suggests that in tropical seas the integrated adaptability would qualify a species for dominating a fouling assemblage despite its short life cycle, rather than the usually assumed only species with long life span. This study reveals the complexity and characteristic dynamics of macrofaunal fouling assemblages in the tropical habitats, and the results would provide valuable knowledge for biodiversity and antifouling research.  相似文献   

3.
One of the fundamental questions in community ecology is whether communities are random or formed by deterministic mechanisms. Although many efforts have been made to verify non-randomness in community structure, little is known with regard to co-occurrence patterns in above-ground and below-ground communities. In this paper, we used a null model to test non-randomness in the structure of the above-ground and below-ground mite communities in farmland of the Sanjiang Plain, Northeast China. Then, we used four tests for non-randomness to recognize species pairs that would be demonstrated as significantly aggregated or segregated co-occurrences of the above-ground and below-ground mite communities. The pattern of the above-ground mite commu- nity was significantly non-random in October, suggesting species segregation and hence interspecific competition. Additionally, species co-occurrence patterns did not differ from randomness in the above-ground mite community in August or in below-ground mite com- munities in August and October. Only one significant species pair was detected in the above-ground mite community in August, while no significant species pairs were recognized in the above-ground mite community in October or in the below-ground mite communities in August and October. The results indicate that non-randomness and significant species pairs may not be the general rule in the above-ground and below-ground mite communities in farmland of the Sanjiang Plain at the fine scale.  相似文献   

4.
Fish assemblage structure in the hypoxic zone in the Changjiang (Yangtze River) estuary and its adjacent waters were analyzed based on data from bottom trawl surveys conducted on the R/V Beidou in June, August and October 2006. Four fish assemblages were identified in each survey using two-way indicator species analysis (TWIA). High fish biomass was found in the northern part, central part and coastal waters of the survey area; in contrast, high fish diversity was found in the southern part of the survey area and the Changjiang estuary outer waters. Therefore, it is difficult to maintain high fishery production when high fish diversity is evenly distributed in the fish community. Fish became smaller and fish size spectra tended to be narrower because of fish species variations and differences in growth characteristics. Fish diversity increased, the age to maturity was reduced and some migrant species were not collected in the surveys. Fish with low economic value, small size, simple age structure and low tropic level were predominant in fish assemblages in the Changjiang estuary and its adjacent waters. The lowest hypoxic value decreased in the Changjiang estuary and its adjacent waters.  相似文献   

5.
Spatio-seasonal patterns of fish diversity,Haizhou Bay,China   总被引:3,自引:0,他引:3  
Spatial-seasonal patterns in fish diversity in Haizhou Bay were studied based on stratified random surveys conducted in 2011.Principal component analysis was conducted to distinguish different diversity components,and the relationships among 11 diversity indices were explored.Generalized additive models were constructed to examine the environmental effects on diversity indices.Eleven diversity indices were grouped into four components:(1) species numbers and richness,(2) heterogeneous indices,(3) evenness,and(4) taxonomic relatedness.The results show that diversity indices among different components are complementary.Spatial patterns show that fish diversity was higher in coastal areas,which was affected by complex bottom topography and spatial variations of water mass and currents.Seasonal trends could be best explained by the seasonal migration of dominant fish species.Fish diversity generally declined with increasing depth except for taxonomic distinctness,which increased with latitude.In addition,bottom temperature had a significant effect on diversity index of richness.These results indicate that substrate complexity and environmental gradients had important influences on fish diversity patterns,and these factors should be considered in fishery resource management and conservation.Furthermore,diversity in two functional groups(demersal/pelagic fishes) was influenced by different environmental factors.Therefore,the distribution of individual species or new indicators in diversity should be applied to examine spatio-seasonal variations in fish diversity.  相似文献   

6.
Habitat plays a critical role in regulating fish community structure. Using the data collected from a monthly trammel net survey in Ma’an archipelago off the east coast of China, we evaluated impacts of five different habitats(artificial reefs, mussel farms, cage aquaculture, rocky reefs and soft bottom) on fish assemblages. This study suggests that artificial reefs(AR) have significantly higher species richness, abundance and diversity than mussel farms(MF) or soft bottom(SB) habitats during most seasons, and that fish taxa in the AR habitats are similar to those in the rocky reef(RR) habitats. Two different fish assemblage patterns were revealed in the study area using non-metric multidimensional scaling ordination: an assemblage dominated by reef fishes(especially by Scorpaenidae species) in AR, RR and cage aquaculture(CA) habitats and an assemblage dominated by Sciaenidae species in MF and SB habitats. We suggest that reef fishes play a key role in differentiating fish community structures in the study area. Although few differences in fish abundance and diversity were found between the CA and SB habitats, a more diverse age structure was observed in the CA habitats. A much more complex fish assemblage and enhanced population of local species were established as a result of the presence of both floating and fixed artificial structures, probably through improved survival rates.  相似文献   

7.
【目的】研究湛江港海域的游泳动物资源结构及多样性特征。【方法】根据2016—2017年湛江港海域4个季度的底拖网渔业资源调查数据,采用相对重要性指数(index of relative importance,IRI)、Margalef丰富度指数(D)、Shannon-Wiener多样性指数(H')、Pielou均匀度指数(J)和ABC曲线(abundance-biomass comparison curve)分析该海域游泳动物的种类组成、优势种和多样性水平等群落结构特征。【结果】该海域共发现游泳动物173种,隶属于16目68科116属;其中鱼类种类数最多(98种,占总种类数的56.7%),以底层鱼类和暖水性鱼类为主;其次是甲壳类(66种,占38.2%),头足类最少(9种,占5.2%)。4个季节的优势种累计有11种(鱼类6种、甲壳类5种),其中条纹叫姑鱼(Johnius fasciatus)是春、夏、秋3个季节的共同优势种。从时间维度上看,秋季的H'、D均为最高,而春季的J最高;从空间维度上看,湛江港口门处S6站位多样性水平相对较高。ABC曲线结果显示,湛江港海域游泳动物群落在冬季受干扰程度高于其它3个季节。【结论】湛江港海域游泳动物种类丰富,其中鱼类是主要的游泳动物类群。  相似文献   

8.
本文对近30 a以来中国上空臭氧总量的时空动态变化特征进行遥感监测与分析。结果表明,中国上空的臭氧总量在持续下降,下降速度低于全球臭氧总量下降速度,而与北半球下降速度基本一致,略低于北半球下降速度。中国臭氧总量每年平均减少0.11%,大约下降0.36 DU,但2000年后中国臭氧总量下降的速度有所减缓,尤其是2005年以来,中国臭氧总量呈上升趋势,这与全球的臭氧总量变化趋势相同。中国臭氧总量的季节变化呈正弦曲线变化,最大和最小值分别出现在3月和10月,平均值大约分别为333.36 DU和284.54 DU。中国臭氧总量季节变化在纬度方向上不明显,而在经度方向上变化较大,同纬度地区臭氧总量,东部地区的大于西部地区的,南北方地区臭氧总量季节变化几乎呈相反的趋势。  相似文献   

9.
Evaluation of spatial-temporal variability of species composition and diversity in oceanic ecosystems is not easy because it is usually difficult to obtain sufficient data quantifying such variability.In this study,we examined pelagic species diversity indicators,species richness,Shannon-Wiener index of diversity and Hurlbert’s species evenness,for fish assemblages from two areas(north and south) in the North Pacific Ocean(2°±12°N,178°E±165°W) during May±July 2008.The assemblages were based on data collected by an onboard scientific observer during a commercial longline fishing trip.The species richness and Shannon-Wiener diversity index of fish assemblages in the northern area were slightly higher than those in the southern area,although these differences were not significant(t test,P.0.05).Non-parametric multidimensional scaling and analysis of similarities indicated that there were significant differences in fish assemblages between the two areas(P,0.01).  相似文献   

10.
The Yellow Sea Cold Water Mass(YSCWM),one of the most vital hydrological features of the Yellow Sea,causes a seasonal thermocline from spring to autumn.The diel vertical migration(DVM) of zooplankton is crucial to structural pelagic communities and food webs,and its patterns can be affected by thermocline depth and strength.Hence,we investigated zooplankton community succession and seasonal changes in zooplankton DVM at a fixed station in the YSCWM.Annual zooplankton community succession was affected by the forming and fading of the YSCWM.A total of 37 mesozooplankton taxa were recorded.The highest and lowest species numbers in autumn and spring were detected.The highest and lowest total densities were observed in autumn(14 464.1 inds./m3) and winter(3 115.4 inds./m3),respectively.The DVM of the dominant species showed obvious seasonal variations.When the YSCWM was weak in spring and autumn,most species(e.g.Paracalanus parvus,Oithona similis,and Acartia bifilosa) stayed above the thermocline and vertically migrated into the upper layer.Calanus sinicus and Aidanosagitta crassa crossed the thermocline and vertically migrated.No species migrated through the stratification in summer,and all of the species were limited above(P.parvus and A.crassa) or below(C.sinicus and Centropages abdominalis)the thermocline.The YSCWM disappeared in winter,and zooplankton species were found throughout the water column.Thus,the existence of thermocline influenced the migration patterns of zooplankton.Cluster analyses showed that the existence of YSCWM resulted in significant differences between zooplankton communities above and below the thermocline.  相似文献   

11.
Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 revealed the spatiotemporal variations of the ambient Si(OH)4:NO3 (Si:N) concentration rations and the seasonal variations of (Si:N) ratios in Jiaozhou Bay and showed that the Si:N ratios were <1 throughout Jiaozhou Bay in spring, autumn, and winter. These results provide further evidence that silicate limits the growth of phytoplankton (i.e. diatoms) in spring, autumn and winter. Moreover, comparison of the spatiotemporal variations of the Si:N ratio and primary production in Jiaozhou Bay suggested their close relationship. The spatiotemporal pattern of dissolved silicate matched well that of primary production in Jiaozhou Bay. Along with the environmental change of Jiaozhou Bay in the last thirty years, the N and P concentrations tended to rise, whereas Si concentration showed cyclic seasonal variations. With the variation of nutrient Si limiting the primary production in mind, the authors found that the range of values of primary production is divided into three parts: the basic value of Si limited primary production, the extent of Si limited primary production and the critical value of Si limited primary production, which can be calculated for Jiaozhou Bay by Equations (1), (2) and (3), showing that the time of the critical value of Si limitation of phytoplankton growth in Jiaozhou Bay is around November 3 to November 13 in autumn; and that the time of the critical value of Si satisfaction of phytoplankton growth in Jiaozhou Bay is around May 22 to June 7 in spring. Moreover, the calculated critical value of Si satisfactory for phytoplankton growth is 2.15–0.76 μmol/L and the critical value of Si limitation of phytoplankton growth is 1.42–0.36 μmol/L; so that the time period of Si limitation of phytoplankton growth is around November 13 to May 22 in the next year; the time period of Si satisfactory for phytoplankton growth is around June 7 to November 3. This result also explains why critical values of nutrient silicon affect phytoplankton growth in spring and autumn are different in different waters of Jiaozhou Bay and also indicates how the silicate concentration affects the phytoplankton assemblage structure. The dilution of silicate concentration by seawater exchange affects the growth of phytoplankton so that the primary production of phytoplankton declines outside Jiaozhou Bay earlier than inside Jiaozhou Bay by one and half months. This study showed that Jiaozhou Bay phytoplankton badly need silicon and respond very sensitively and rapidly to the variation of silicon. This study was funded by NSFC (No. 40036010) and subsidized by Special Funds from National Key Basic Research Program of P. R. China (G19990437), the Postdoctoral Foundation of Ocean University of Qingdao, the Director's Foundation of the Beihai Monitoring Center of the State Oceanic Administration and the Foundation of Shanghai Fisheries University.  相似文献   

12.
A study on the assemblage composition and vertical distribution of larval fish was conducted in the southern area of the Moroccan Atlantic coast in Autumn 2011. A total of 1 680 fish larvae taxa were identified from 21 families. The majority of the larvae were present in the upper layers. Clupeids were the most abundant larvae taxa followed by Myctophidae, Gadidae and Sparidae, hence the larval fish assemblages(LFA) were variable in different depth layers. Total fish larvae showed a preference for surface layers, and were mainly found above 75 m depth, with some exceptions. The maximum concentration of fish larvae was concentrated up to 25 m essentially above the thermocline, where chlorophyll a and mesozooplankton were abundant. Spatially, neritic families were located near the coast and at some offshore stations especially in the northern part, while oceanic families were more distributed towards offshore along the study area. Cluster analysis showed a segregation of two groups of larvae. However, a clear separation between neritic families and oceanic families was not found. Multivariate analysis highlighted the relationship between the distribution of larvae of different families and environmental parameters. Temperature and salinity seem to have been the factors that acted on associations of fish larvae. Day/night vertical distributions suggest there was not a very significant vertical migration, probably due to adequate light levels for feeding.  相似文献   

13.
In 2012, an artificial reef system was deployed in Xiangshan Bay, China, to enhance its fishery resources. To determine the effect of the artificial reef system on the demersal nekton assemblages, a beforeafter- control-impact study design was applied. Comparisons of assemblages from impact and control habitats revealed that the assemblage in the impact area had a gradual response to reef deployment. The assemblages in the impact and control areas changed in different ways after reef deployment. During the study period, total biomass, species richness and average body weight in the control area remained relatively stable, whereas there were significant increases in these indicators in the impact area. Responses to the reefs differed among nekton species, inducing assemblage succession in the reefs post-deployment. Sparus macrocephalus and Cynoglossus abbreviatus benefited most from reef deployment. Conversely, smallsized shrimp Palaemon gravieri showed a progressive decrease in biomass following reef deployment. Overall, the artificial reef system diversified the demersal nekton assemblage, enhanced the total biomass, and increased the proportion of large-sized species.  相似文献   

14.
Reservoirs are important artificial ecosystems that modify the hydrological and ecological characteristics of a river.Knowledge of the basic characteristics of fish assemblages in reservoirs is a first step toward the development of effective conservation policies.We used the information collected over a10-year period(2006-2015)to assess the structure of the fish assemblages in the Three Gorge Reservoir(TGR)in a river-dam gradient.Three fish zones were detected in TGR.Species richness was the highest in the upper zone and lowest in the lower zone.The riverine zones were dominated by rheophilic species Coreius guichenoti and Pelteobagrus vachelli.The transitional zones were dominated by Coreius heterodon and Rhinogobio cylindricus.The lacustrine zones were dominated by eurytopic species Hypophthalmichthys molitrix,Aristichthys nobilis,Hemiculter bleekeri and Cyprinus carpio.For the functional characteristics,fish assemblages in riverine and transitional zones were dominated by insectivorous species,equilibrium strategists and rheophilic species(e.g.,Coreius heterodon and Coreius guichenoti).In lacustrine zones,the fish assemblage was dominated by habitat generalists common to lakes and reservoirs(e.g.,Hemiculter bleekeri,Hypophthalmichthys molitrix,Aristichthys nobilis).Moreover,18 exotic species(e.g.,Protosalanx hyalocranius,Ictalurus punctatus,Megalobrama amblycephala,Tilapia)were collected in TGR,most of which only existed in the lacustrine zone.The results highlight the importance of freely flowing riverine reaches for conserving native fish in the upper Changjiang River and adaptive management strategies for fisheries in TGR.  相似文献   

15.
Fouling diatoms are a main component of biofilm,and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater,on the Yantai coast,northern Yellow Sea,China,using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3,7,14,and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca,Nitzschia,Navicula,Amphora,Gomphonema,and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions,we found that Cylindrotheca grew very fast,which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18 S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.  相似文献   

16.
INTRODUCTIONNandPinputtedintoJiaozhouBaybyriversandbysewageeffluentsofcities ,havemadetheBaybecomemoreandmoreeutrophicdaybyday .Shen ( 1994)thoughtthatphytoplanktongrowthwaslimitedbythechangefromnitrogentophosphorous ;andthatthesilicateconcentrationinJiaozh…  相似文献   

17.
Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994 (12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation of the ambient concentration Si∶DIN and Si∶16P ratios and the seasonal variation of Jiaozhou Bay Si∶DIN and Si∶16P ratios showing that the Si∶DIN ratios were <1 throughout the year in Jiaozhou Bay; and that the Si∶16P ratios were <1 throughout Jiaozhou Bay in spring, autumn and winter. The results proved that silicate limited phytoplankton growth in spring, autumn and winter in Jiaozhou Bay. Analysis of the Si∶DIN and Si∶P ratios showed that the nutrient Si has been limiting the growth of phytoplankton throughout the year in some Jiaozhou Bay waters; and that the silicate deficiency changed the phytoplankton assemblage structure. Analysis of discontinuous 1962 to 1998 nutrient data showed that there was no N or P limitation of phytoplankton growth in that period. The authors consider that the annual cyclic change of silicate limits phytoplankton growth in spring, autumn and winter every year in Jiaozhou Bay; and that in many Jiaozhou Bay waters where the phytoplankton as the predominant species need a great amount of silicate, analysis of the nutrients N or P limitation of phytoplankton growth relying only on the N and P nutrients and DIN∶P ratio could yield inaccurate conclusions. The results obtained by applying the rules of absolute and relative limitation fully support this view. The authors consider that the main function of nutrient silicon is to regulate and control the mechanism of the phytoplankton growth process in the ecological system in estuaries, bays and the sea. The authors consider that according to the evolution theory of Darwin, continuous environmental pressure gradually changes the phytoplankton assemblage's structure and the physiology of diatoms. Diatoms requiring a great deal of silicon either constantly decrease or reduce their requirement for silicon. This will cause a series of huge changes in the ecosystem so that the whole ecosystem requires continuous renewal, change and balancing. Human beings have to reduce marine pollution and enhance the capacity of continental sources to transport silicon to sustain the continuity and stability in the marine ecosystem. This study was funded by the NSFC (No. 40036010) and subsidized by Special Funds from the National Key Basic Research Program of P. R. China (G199990437), the Postdoctoral Foundation of Ocean University of Qingdao, the Director's Foundation of the Beihai Monitoring Center of the State Oceanic Administration and the Foundation of Shanghai Fisheries University.  相似文献   

18.
本文以厦门市为例,基于MODIS影像反演的大气气溶胶光学厚度(AOD),利用空间自相关和景观格局指数从数量、形态和结构方面综合分析了2014年各月份(5月和9月除外)AOD时空格局变化。结果表明,研究区AOD具有明显的时空分布差异,林地上空的AOD处于较低等级,建设用地上空AOD大部分处于中高等级;AOD在春夏季较大,在秋冬季较小。AOD分布存在显著正空间自相关性,而且主要存在高高(HH)、低低(LL)、高低(HL)3种聚集模式。低低聚集模式主要分布在厦门市的北部山区;高高(HH)和高低(HL)模式主要分布在本岛东北部新城和本岛外各新城的城区。在景观格局指数方面,从秋冬季节到春夏季节期间,研究区气溶胶光学厚度高等级斑块增加,景观结构趋于复杂,景观异质性增加。对AOD时空格局变化进行多指标综合分析可以更加深入、细致、全面地刻画气溶胶的变化规律,有助于精确评估气溶胶对环境、气候等的影响,为城市可持续发展提供决策支持。  相似文献   

19.
青藏高原-热带印度洋地区大气热源的时空变化特征   总被引:1,自引:0,他引:1  
为了寻求青藏高原一热带印度洋地区大气热源空间变化的敏感区,进一步深入研究季风的形成、变异和预测,利用NCEP1979-2008年的再分析资料计算分析了青藏高原一热带印度洋地区30年来不同季节大气热源分布的气候特征,并且利用经验正交函数分解研究了该区大气热源在夏、冬季的时空变化特征。结论如下:春季大气热源有明显的经向差异;夏季的热源明显比春季的热源强度强,范围广,热源最强中心在孟加拉湾北部大陆边缘;秋季热源区域明显南缩,热源强度较夏季明显减弱;冬季大气热源呈西西南一东东北方向分布,大气热源位置继续南移。对于夏季,前3个模态分别反映了青藏高原一热带印度洋地区大气热源的纬向差异型、经向差异型、西北一东南分布型。对于冬季,前3个模态分别反映了青藏高原一热带印度洋地区大气热源的经向差异主导型、经向差异型、纬向差异型。  相似文献   

20.
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